The present invention relates generally to the processing of zinc mine tailings to recover various components, including metals. More specifically, the present invention relates to the processing of zinc mine tailings to separate and remove the zinc powder, copper and various other semi-precious and precious metals without the use of any chemicals, and the integrated use of the separated carbon in an integrated cogeneration plant.
Zinc mine tailings are a product of the smelting of zinc, and often contain mixtures of coal, zinc powder, copper, lead and certain precious metals such as gold or silver. It has been estimated that zinc mine tailings contain up to 18% by volume of zinc and up to 28% by volume of copper. Nevertheless, because of the difficulty, expense and environmental hazards relating to the separation of these desired metals, no such separation is generally attempted. It is thus commonplace for zinc mine tailings to be simply piled and used as landfill. Unfortunately, this method of zinc mine tailing disposal often results in the leaching of copper, lead and other metals into the ground water.
Various methods of attempting to obtain valuable metals from zinc mine tailings are known in the prior art. However, the prior art methods involve the use of potentially dangerous and environmentally hazardous chemicals. Non-chemical methods of precious metal recovery using aqueous separation means are shown in U.S. Pat. No. 4,428,830. However, these aqueous systems are generally of the handheld variety and do not provide an industrial application as for an integrated cogeneration plant.